Oh! This one is easy! So what you need to do is Do the Blah Blah Blah ("chatting") , then make her join the party. Then Make a CONTROL SWITCH and name it so you know which one it is, then make a new page and make the condition that that switch is on, then click the Erase event command which is on the first page of events. Also you should make a Show Text that says she is in your party. Here is a simple version:
1. Show Text ect ect ect
2. Add actor: whatever her name is
3. Show Text: So and so is in your party
4. Switch So and So is in party=ON
5. New Page condition: So and so is in party Switch is ON
6. Erase event
Ta da! ;) EDIT: Just in case you wanted to know, what your problem was was (lol was was was) that on your second page, if it is just blank, the event is just still there, she should just not have a graphic.